Singapore’s Prime Minister Lee Hsien Loong is suing a vocal critic of his government for defamation for sharing an article on Facebook that suggested he was involved in Malaysia’s multibillion dollar 1MDB financial scandal, according to local media.

He resorted to legal action only after Leong Sze Hian, a financial adviser, failed to comply with a letter sent by the prime minister’s lawyers demanding a public apology and damages over the November 7 post, The Straits Times reported.

The article, published by Malaysian outlet The Coverage, claimed Malaysia’s disgraced former prime minister Najib Razak – facing dozens of criminal charges over his links to the scandal – had dealt with Lee to secure Singapore banks’ help in relation to the 1MDB funds.

Before this legal suit, the Singapore government had already tried to take action against the authors of the original article, describing the allegations as “fake news and libellous”.

“Those allegations are false and baseless and constitute a very serious libel against our client, and disparage and impugn his character, credit and integrity,” Lee’s legal team said in the letter to Leong, according to The Straits Times.

Lee had been “gravely injured in his character and reputation, and has been brought into public scandal, odium and contempt,” the lawyers wrote.

When contacted by the South China Morning Post, Leong said: “For legal reasons, I am unable to comment on my case. In my defence, I can say that this is a fight not between me and the prime minister, but between the people and him for freedom of expression. transparency and democracy. I am bewildered as to why he is suing me for defamation.”

The author and columnist has for years assailed Lee’s ruling People’s Action Party (PAP) over its economic policy, and was previously the president of Maruah, the city state’s main independent human rights NGO.

Lee’s decision to personally sue Leong follows legal action that has been taken by the authorities against other parties who disseminated The Coverage’s report, which was sourced from States Times Review – an online portal run by an Australia-based dissident.

Singaporean authorities ordered local internet service providers to block States Times Review over the site’s refusal to take down the piece. Most of States Times Review’s stories are one-sided commentaries – often not based on facts.

As local authorities moved to block access to the website, they also sought Facebook’s help to take down the post involving Lee. The social media giant’s refusal to do so elicited a furious response from Lee’s administration, with the law ministry stating that the US company “cannot be relied upon to filter falsehoods or protect Singapore from a false information campaign”.

Lee and previous leaders of Singapore, including his late father Lee Kuan Yew and predecessor Goh Chok Tong, have a track record of initiating legal action as a remedy to being defamed.

While rights groups say doing so chills free speech, the leaders say they have no other way to protect their reputation.